<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子模型</title>
    <style>
        .wai{
            border: 1px solid red;
            width: 200px;
            height: 200px;
            /*设置内边距*/
        }
        .nei{
            border: 1px solid blue;
            width: 100px;
            height: 100px;
            /*设置外边距*/
            /*margin-top: 50px;*/
            /*margin-left: 50px;*/
            /*margin-right: 50px;*/
            /*margin-bottom: 50px;*/

            /*可以直接设置所有外边距都是50px*/
            /*margin: 50px;*/

            /*上、右、下、左*/
            /*margin: 70px 35px 30px 65px;*/
        }
    </style>
</head>
<body>
<div class="wai">
    <div class="nei">

    </div>
</div>
</body>
</html>